Intravascular cuff

ABSTRACT

An intravascular cuff acts as a lining between a native vessel and an intravascular prosthetic device. During deployment, the ends of the cuff curl back upon themselves and are capable of trapping native tissue, such as valve leaflet tissue, between the ends. The cuff creates a seal between the vessel and the prosthetic, thereby preventing leakage around the prosthetic. The cuff also traps any embolic material dislodged from the vessel during expansion of the prosthetic.

RELATED APPLICATIONS

This application is a divisional U.S. patent application Ser. No.14/929,140, filed Oct. 30, 2015 entitled Intravascular Cuff, which is acontinuation of U.S. patent application Ser. No. 14/174,809, filed Feb.6, 2014 entitled Intravascular Cuff (now U.S. Pat. No. 9,180,003 issuedNov. 10, 2015), which is a divisional of U.S. patent application Ser.No. 11/442,371 filed May 26, 2006 entitled Intravascular Cuff (now U.S.Pat. No. 8,663,312 issued Mar. 4, 2014), which is related to and claimspriority benefit of U.S. Provisional Patent Application Ser. No.60/685,433, filed May 27, 2005, entitled Intravascular Cuff, all ofwhich are hereby incorporated by reference herein in their entireties.This application also incorporates by reference U.S. patent applicationSer. No. 11/443,814 filed May 30, 2006 entitled Stentless SupportStructure; U.S. Provisional Patent Application Ser. No. 60/685,349,filed May 27, 2005, entitled Stentless Support Structure; and U.S.Provisional Patent Application Ser. No. 60/709,595, filed Aug. 18, 2005,entitled Stentless Support Structure.

BACKGROUND OF THE INVENTION

There has been a significant movement toward developing and performingcardiac and other surgeries using a percutaneous approach. Through theuse of one or more catheters that are introduced through, for example,the femoral artery, tools and devices can be delivered to a desired areain the cardiovascular system to perform any number of complicatedprocedures that normally otherwise require an invasive surgicalprocedure. Such approaches greatly reduce the trauma endured by thepatient and can significantly reduce recovery periods. The percutaneousapproach is particularly attractive as an alternative to performingopen-heart surgery.

Valve replacement surgery provides one example of an area wherepercutaneous solutions are being developed. A number of diseases resultin a thickening, and subsequent immobility or reduced mobility, of valveleaflets. Valve immobility leads to a narrowing, or stenosis, of thepassageway through the valve. The increased resistance to blood flowthat a stenosed valve presents eventually leads to heart failure anddeath.

Treating severe valve stenosis or regurgitation has heretofore involvedcomplete removal of the existing native valve followed by theimplantation of a prosthetic valve. Naturally, this is a heavilyinvasive procedure and inflicts great trauma on the body leading usuallyto great discomfort and considerable recovery time. It is also asophisticated procedure that requires great expertise and talent toperform.

Historically, such valve replacement surgery has been performed usingtraditional open-heart surgery where the chest is opened, the heartstopped, the patient placed on cardiopulmonary bypass, the native valveexcised and the replacement valve attached. A proposed percutaneousvalve replacement alternative method is disclosed in U.S. Pat. No.6,168,614 (the entire contents of which are hereby incorporated byreference) issued to Andersen et al. In this patent, the prostheticvalve is collapsed to a size that fits within a catheter. The catheteris then inserted into the patient's vasculature and moved so as toposition the collapsed valve at the location of the native valve. Adeployment mechanism is activated that expands the replacement valveagainst the walls of the body lumen. The expansion force pushes theleaflets of the existing native valve against the lumen wall thusessentially “excising” the native valve for all intents and purposes.The expanded structure, which includes a stent configured to have avalve shape with valve leaflet supports, is then released from thecatheter and begins to take on the function of the native valve. As aresult, a full valve replacement has been achieved but at asignificantly reduced physical impact to the patient.

However, this approach has decided shortcomings. One particular drawbackwith the percutaneous approach disclosed in the Andersen '614 patent isthe difficulty in preventing leakage around the perimeter of the newvalve after implantation. As the tissue of the native valve remainswithin the lumen, there is a strong likelihood that the commissuraljunctions and fusion points of the valve tissue (as pushed against thelumen wall) will make sealing of the prosthetic valve around theinterface between the lumen and the prosthetic valve difficult.

Other drawbacks of the Andersen '614 approach pertain to its reliance onstents as support scaffolding for the prosthetic valve. First, stentscan create emboli when they expand. Second, stents are typically noteffective at trapping the emboli they dislodge, either during or afterdeployment. Third, stents do not typically conform to the features ofthe native lumen in which they are placed, making a prosthetic valvehoused within a stent subject to paravalvular leakage. Fourth, stentscan be hard to center within a lumen.

As to the first drawback, stents usually fall into one of twocategories: self-expanding stents and expandable stents. Self-expandingstents are compressed when loaded into a catheter and expand to theiroriginal, non-compressed size when released from the catheter. Balloonexpandable stents are loaded into a catheter in a compressed but relaxedstate. A balloon is placed within the stent. Upon deployment, thecatheter is retracted and the balloon inflated, thereby expanding thestent to a desired size. Both of these stent types exhibit significantforce upon expansion. The force is usually strong enough to crack or popthrombosis, thereby causing pieces of atherosclerotic plaque to dislodgeand become emboli. If the stent is being implanted to treat a stenosedvessel, a certain degree of such expansion is desirable. However, if thestent is merely being implanted to displace native valves, less forcemay be desirable to reduce the chance of creating emboli.

As to the second drawback, if emboli are created, expanded stentsusually have members that are too spaced apart to be effective to trapany dislodged material. Often, secondary precautions must be takenincluding the use of nets and irrigation ports.

The third drawback is due to the relative inflexibility of stents.Stents rely on the elastic nature of the native vessel to conform aroundthe stent. Stents used to open a restricted vessel do not require a sealbetween the vessel and the stent. However, when using a stent todisplace native valves and house a prosthetic valve, a seal between thestent and the vessel is necessary to prevent paravalvular leakage. Dueto the non-conforming nature of stents, this seal is hard to achieve,especially when displacing stenosed valve leaflets.

The fourth drawback is that stents can be hard to center within a lumen.Stenosed valves can have very irregular shapes. When placing a stentwithin an irregularly shaped, calcified valve, the delivery catheter canbecome misaligned causing the stent to be delivered to an off-centerlocation, such as between two calcified valve leaflets. Expanding thestent in such a location can result in poor seating against the lumenwalls and significant paravalvular leakage or a non-functioningprosthetic valve.

BRIEF SUMMARY OF THE INVENTION

The present invention addresses the aforementioned drawbacks byproviding a tubular or toroidal cuff that surrounds a native valve andcreates an ideal implantation site for a stent. The cuff is constructedof at least one fine braided strand of a material having super-elasticor shape memory characteristics, such as Nitinol. The cuff is tubularwhen in an extended configuration within a delivery catheter. Whenreleased from the delivery catheter, the ends of the cuff curl back onthemselves, trapping the native valve leaflets between the curled ends.The center of the cuff does not expand as much as the ends, therebyleaving a reduced diameter lumen that is ideal for receiving anintravascular device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a preferred device of the present invention;

FIG. 2 is an end view of the device of FIG. 1;

FIG. 3 is a cutaway view of a device of the present invention beingdeployed in a native vessel;

FIG. 4 is a cutaway view of a device of the present invention beingdeployed in a native vessel;

FIG. 5 is a cutaway view of a device of the present invention beingdeployed in a native vessel;

FIG. 6 is a cutaway view of a device of the present invention beingdeployed in a native vessel;

FIG. 7 is a cutaway view of a device of the present invention beingdeployed in a native vessel;

FIG. 8 is a side view of a preferred device of the present invention;

FIG. 9 is an end view of the device of FIG. 1 in an expanded state; and,

FIG. 10 is a side view of the device of FIG. 1 in an expanded state.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the Figures and first to FIGS. 1 and 2, there is shownan intravascular cuff 10 of the present invention. The cuff 10 is shownin its relaxed, expanded configuration and comprises a generally tubularstructure having two flared ends 12 and 13 and a narrow tubular body 14.The elongated tube that is used to construct the cuff 10 is formed fromat least one braided strand capable of exhibiting super-elasticity orshape memory. In one embodiment, the elongated tube is folded in halfupon itself such that the first end 12 becomes a folded end and thesecond end 13 includes a plurality of unbraided strands. The tubularbody is thus two-ply. The strand or strands may be fibrous, non-fibrous,multifilament, or monofilament. Nitinol is an example of a preferablematerial for the strand(s). The strand(s) are braided to allow thedevice to be expanded longitudinally into a very long, thin tube capableof being placed in a very small delivery catheter. Preferably, the cuff10 can be inserted into a delivery catheter that is sized 16 Fr orsmaller. The braids are tight enough to catch emboli that may bedislodged from a lumen wall, while still allowing the thin, elongatedconfiguration.

The cuff 10 includes a central lumen 16, which extends through theentire cuff 10. The central lumen 16 is sized to receive a deliverycatheter for a prosthetic device such as a stent. Preferably, the lumen16 has ends that flare or mushroom gently, thereby creating a funnel forguiding a delivery catheter into the center of the lumen 16.

FIGS. 1 and 2 show that, even when the cuff 10 is in a radiallyexpanded, relaxed configuration, the lumen 16 is small and very welldefined. Thus, when deployed, the mushroom-like ends 12 and 13 expandand conform to the shape of the target vessel lumen while the cuff lumen16 remains well defined and relatively centered within the cuff 10.Thus, the cuff 10 presents an ideal target and guide for a physicianplacing a prosthetic valve or stent within the cuff. Preferably, thecuff 10 is radiopaque, making the target it presents even moreaccessible.

The deployment of the cuff 10 is illustrated in FIGS. 3-7. Beginningwith FIG. 3, a cuff 10 is percutaneously delivered to a targetedstenosed valve 18 via a delivery catheter 20. The catheter 20 isadvanced until a distal end 22 of the catheter is past the targetedvalve 18.

As seen in FIG. 4, the delivery catheter 20 is then retracted relativeto the cuff 10. Doing so releases the distal end 12, which immediatelyflares outwardly. With the end 12 in contact with the vessel walls, thephysician may pull gently on the catheter 20 and the cuff 10 to abut theend 12 of the cuff 10 against the stenosed valve 18, thereby ensuringproper placement of the cuff 10.

Next, as shown in FIG. 5, the catheter 20 is retracted fully, allowingthe proximal end 13 of the cuff 10 to expand against the vessel walls ona proximal side of the stenosed valve 18. The stenosed valve 18 is nowcompletely encased in the braided mesh of the cuff 10, and the cuff isready to receive a prosthetic device such as a stented prosthetic valve24 (FIGS. 6 and 7). Notably, despite the irregular shape of the stenosedvalve 18, the central lumen 16 of the cuff presents a path through thetargeted site and provides an ideal receiving seat for the prostheticvalve 24.

In FIG. 6, the stented prosthetic valve 26 is percutaneously deliveredto the cuff 10 via a catheter 28. The catheter 28 is inserted directlyinto the cuff lumen 16, using the funneled end 13 as a guide.

In FIG. 7, the prosthetic valve 26 is expanded and the catheter 28removed. Expanding the stented prosthetic 26 necessarily expands thecentral lumen 16. Doing so causes the cuff 10 to shorten and the flaredends 12 and 13 to fold back further, placing a more secure grip on thestenosed valve 18. Furthermore, any plaque or other material dislodgedduring the expansion of the prosthetic 26 is trapped by the ends 12 and13. The cuff 10 provides an optimal seat for the prosthetic 26 andprevents any blood from leaking around the prosthetic valve 26. Overtime, the braided strand(s) promote ingrowth, further improving the sealprovided by the cuff 10.

One embodiment of the present invention uses a non-woven fabric tofurther enhance the seal created between the cuff 10 and the vesselwalls. FIG. 8 shows a cuff 10 having a two-ply body with a material 32trapped between the two layers. The non-woven fabric expands easily suchthat the expansion characteristics of the cuff 10 are not affected.Additionally, the material 32 may be impregnated with a therapeuticcompound. The material 32 can consist of a non-woven material, a wovenfabric, a polymer or other material.

Referring now to FIGS. 9 and 10, the cuff 10 originally depicted inFIGS. 1 and 2 is shown with a plug 30 expanding the central lumen 16 ofthe cuff 10. This demonstrates how the cuff 10 shortens and the ends 12and 13 fold back when the lumen 16 is expanded. Expanding the centrallumen 16 thus causes the ends 12 and 13 to create a strong grip onnative tissues, such as valve leaflets, lodged between the ends 12 and13.

In another embodiment, on deployment from a catheter, the ends of theelongate tube roll outwardly toward the middle of the device.Alternatively, the end can roll inwardly toward the middle of thedevice. This action would be facilitated by use of a super-elastic orshape memory material such as Nitinol.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

1. A method of preventing leakage between a prosthetic valve and avessel wall comprising: deploying a self-expanding mesh cuff having atleast two-ply in the vessel prior to implanting the prosthetic valve,said mesh cuff including a center body portion and two end portions oneither side of the center body portion; allowing the end portions toexpand and form a seal against the vessel wall while the center bodyportion of said cuff forms an open lumen; implanting the prostheticvalve within said open lumen after the step of allowing the end portionsto expand; wherein at least one of said end portions mushrooms whenexpanded such that a gap is created between the plies of the endportions, thereby creating a funnel for guiding a delivery catheter intosaid open lumen in said cuff, and allowing an outer ply to conformagainst native tissue while an inner ply creates said funnel; andwherein allowing the end portions to expand causes at least one of saidend portions to fold.
 2. The method of claim 1 further comprisingexpanding the prosthetic valve within the open lumen.
 3. The method ofclaim 2 wherein expanding the prosthetic valve within the open lumencauses the body portion of the cuff to expand.
 4. The method of claim 3wherein causing the body portion to expand causes the body portion toshorten longitudinally.
 5. A method of preventing paravalvular leakagecomprising: placing a device having at least two ply within a targetvalve such that end portions of said device are located on either sideof the target valve; expanding an outer ply of at least end portionagainst the native tissue while an inner ply of the at least one endportion remains less expanded, thereby preventing the inner ply frominterfering with the conformation of the outer ply of the at least oneend portion; whereby material joining the inner and outer plies of theat least one end portion form a funnel leading into a lumen of thedevice.
 6. The method of claim 5 further comprising providing a materialtrapped between in the inner and outer plies.
 7. The method of claim 5wherein expanding the outer ply of the at least one end portion causesthe outer ply to fold back on itself.
 8. The method of claim 5 furthercomprising inserting a prosthetic within lumen of the device.
 9. Themethod of claim 8 further comprising expanding the prosthetic within thelumen of the device.